An openly gay police officer says he has been openly taunted and harassed by colleagues who routinely call him an anti-gay slur, mock his manliness and ridicule him while he’s escorting prisoners.

“I always wanted to be a police officer, and I want to stay a police officer, but it’s very difficult to cope with what’s going on,” said William Harrington, 30, who is suing the NYPD for discrimination.

An officer for five years, Harrington said that since coming out to a colleague in 2003, he has been assigned to undesirable shifts and beats, seen his once- promising career hit a standstill and become a prime target for taunts.

One colleague told him he should carry a female prisoner’s purse because it would be a good look for him, Harrington said.

“It’s a very difficult time,” Harrington said.

He said that while working in Brooklyn’s 75th Precinct, he was repeatedly called a “faggot,” found his locker upended and received an anony mous note that read, “Die, you c- – -.”

He was at a domestic-disturbance call on Dec. 15, 2003, when, Harrington said, one of his co-workers turned his back on a female beating victim to call him “a f- – -ing faggot.”

The cop said the harassment continued after his transfer to Brooklyn’s 79th Precinct, where his paperwork to take a day off to go to Gay Day at the Six Flags Great Adventure theme park was mysteriously “lost.”

Harrington brought his partner with him to the precinct’s Christmas party. His suit, filed this week in Manhattan, said that when he introduced his partner to colleagues, one spat out his drink and laughed.

The fed-up officer filed a complaint with the Equal Employment Opportunity Commission, which found his discrimination complaints were “substantiated,” the suit says.

He was transferred in September 2006 to the 6th Precinct in Greenwich Village. Once he got there, the complaint says, he found the atmosphere just as hostile.

One of his co-workers said all gays “should be shot,” and others routinely used anti-gay slurs, the suit says.

“It has not been a pleasant journey for him, to say the least,” said his lawyer, George Rosenbaum.

He is seeking unspecified money damages.

A spokeswoman for the city Law Department declined comment, saying it had not yet seen the suit.